Southeastern Arkansas Research Articles

Potassium losses in runoff from cotton production fields

AbstractPotassium (K) loss in runoff represents a potential financial concern since fertilizer‐K is routinely applied to sustain optimal crop K nutrition and yield potential. Our research objectives were to quantify and characterize the soluble‐K loss in runoff from fields used for continuous cotton (Gossypium hirsutum L.) production while determining if the time of the year (growing season vs. nongrowing season), type of hydrological event (irrigation vs. rainfall), and cover crops influence K loss in runoff. Field‐scale, edge‐of‐field monitoring of runoff water and its soluble‐K concentration was performed on 10 site years in southeastern Arkansas across three production seasons. The mean K loss in surface runoff per event was 0.98 kg ha−1 across all sites and events (n = 304). The relationship between loss of K mass to runoff volume was positive and significantly correlated (p < 0.0001) when both variables were transformed by the natural logarithm. K loss during the growing season was significantly higher (p < 0.001) in the cotton growing season whereas K loss resulting from runoff events generated by either irrigation or rainfall was not significant. Additionally, losses from fields with cover crops were significantly larger (p < −0.05) than from fields without covers. Cumulative annual‐K loss, between annual fertilizer‐K applications, averaged 32.2 kg K ha−1 across all site years representing a significant economic loss to replace the lost K with fertilizer. This study illustrates the increased risk of K losses on poorly drained soils in the Southeastern United States. Runoff‐K loss represents a significant amount of K that requires additional research on how to mitigate these losses.

Quantifying Spatial Drought Propagation Potential in North America Using Complex Network Theory

AbstractDroughts have a dominant three‐dimensional (3‐D) spatiotemporal structure typically spanning hundreds of kilometers and often lasting for months to years. Here, we introduced a novel framework to explore the 3‐D structure of the evolution of droughts based on network theory concepts. The proposed framework is applied to identify critical source regions responsible for large‐scale drought onsets during 1901–2014 for the North American continent using the Standardized Precipitation Evaporation Index (SPEI). We built a spatial network connecting the drought onset timings for the North American continent. Using a spatially weighted network partitioning algorithm, the whole continent is then classified into regional spatial drought networks (RSN), where droughts are more likely to propagate within these regional systems. Finally, a customized network metric was applied to identify locations (source regions) where the drought onsets further propagate to other areas within the regional spatial network. Our results indicated that the West coast, Texas coastal region, and Southeastern Arkansas as major source regions through which atmospheric drought propagates to Western, South Central, and Eastern North America. The formation of drought source regions are due to presence of high pressure ridges and anomalous wind patterns. Furthermore, our results indicate that the drought propagation from these source regions may be due to inadequate moisture transport. The proposed framework can help to develop an early warning detection system for droughts and other spatially extensive extreme events such as heatwaves and floods.

Erratum: Evidência geoquímica e isotópica de fluxo ascendente de fluido salino para o aquífero aluvial do Vale do Rio Mississippi, sudeste do Arkansas, EUA

Erratum: Evidência geoquímica e isotópica de fluxo ascendente de fluido salino para o aquífero aluvial do Vale do Rio Mississippi, sudeste do Arkansas, EUA

Tree-level Growth of Four Oak Species in a Bottomland Hardwood Plantation: Implications for Silvicultural Treatments

Abstract A 41-year-old bottomland hardwood plantation experiment located in southeastern Arkansas was revisited in 2017 to evaluate basal area increment (BAI) of four oak species [cherrybark oak (Quercus pagoda Raf.), swamp chestnut oak (Q. michauxii Nutt.), Nuttall oak (Q. texana Buckl.), and water oak (Q. nigra L.)] planted in monoculture in relation with species, spacing, thinning, and neighborhood competition. Species had a significant effect on BAI (P = 0.04), with cherrybark oak and Nuttall oak demonstrating the greatest (21.5 ± 2.5 cm2 year−1) and lowest (12.7 ± 2.9 cm2 year−1) growth rates, respectively, whereas BAI declined significantly with increasing competition (P = 0.03). However, rates of growth decline with competition did not differ between species (P > 0.05 for competition × species term), and thinning and spacing treatments had no effect on BAI (P > 0.05). We recommend that repetitive thinning, rather than a single thinning, would be appropriate to maintain a positive impact on oak growth. Managing stand density would not only provide opportunities for improving timber production, but also would enhance ecological benefits (e.g., wildlife habitat) through diversification of structure within monoculture plantations.

Behind the Scenes of Hollywood: An Archaeology of Reproductive Oppression at the Intersections

ABSTRACTReproductive oppression is the control and exploitation of women, girls, and individuals through our bodies, sexuality, labor, and reproduction. This archaeological research utilizes intersectionality and praxis as analytic tools to uncover reproductive oppression in the past and embolden reproductive justice in the present. At the nineteenth‐century Hollywood Plantation in southeastern Arkansas, the materiality of the past—census records, medicine bottles, toys, and grave markers—provides a lens onto the deep history of reproductive oppression and the ways people responded to it. By situating individuals and artifacts at the intersections, I interpret various artifacts from differing positionalities, focusing and refocusing the lens on all of the women who lived and worked in the house to understand the ways reproduction shaped their lives over time and to draw connections between the control over Black women's bodies exercised by slaveholders and the contemporary trend to limit women's control of their reproductive health. [historical archaeology, reproductive oppression, intersectionality, praxis, Arkansas]

The influence of repeated prescribed fire on decomposition and nutrient release in uneven-aged loblolly\u2013shortleaf pine stands

BackgroundRepeated use of prescribed fire in Southern US pine stands has the potential to alter litter quality as well as forest floor mineralization, which may reduce nutrient availability. There are few studies that have investigated the effects of prescribed fire on litter decomposition in stands with frequent, partial harvests. To better understand the effects of the long-term use of prescribed fire coupled with periodic harvesting, we monitored foliar litter mass loss and nutrient dynamics in three loblolly pine (Pinus taeda L.)–shortleaf pine (Pinus echinata Mill.) stands located in southeastern Arkansas, USA. A reciprocal transplant method and the litterbag technique were used to determine the effects of litter source (litter quality) and litter location (environmental conditions) on decomposition.ResultsLong-term use of prescribed fire in periodically harvested stands had minimal influence on mass loss and nutrient dynamics. The proportion of foliar litter remaining after approximately 16 months did not significantly differ by litter source or location. Decay constants associated with litter incubated during the first 30 days of the study differed significantly by litter source, but thereafter were similar. Initial concentrations of phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) were 13 to 22% greater for litter originating from the burn than for litter originating from the control treatment, but differences in nutrient concentrations were not found to alter decomposition or nutrient dynamics. Thirteen percent more K was lost from litter originating from the burn compared to litter originating from the control treatment, but losses of other nutrients did not differ between litter sources. Soil and forest floor environmental conditions did not differ between treatment locations, which likely contributed to the similar decomposition rates in the two treatment locations. The rapid growth of understory and the maintenance of similar canopy conditions as a result of harvesting were likely responsible for the similarity in environmental conditions.ConclusionsRepeated dormant season prescribed fire in these loblolly–shortleaf pine stands did not appear to have a substantial influence on mass loss or nutrient release from litter. Land managers who utilize prescribed fire with periodic harvesting in relatively mesic upper Gulf Coastal Plain pine forests likely will not alter litter decomposition or nutrient dynamics.

Organochloride Pesticides Present in Animal Fur, Soil, and Streambed in an Agricultural Region of Southeastern Arkansas

Organochloride Pesticides Present in Animal Fur, Soil, and Streambed in an Agricultural Region of Southeastern Arkansas

Spatial analysis of groundwater chloride anomalies, earthquake sand-blows, and surface soils in the Mississippi River Valley alluvium in southeastern Arkansas

Groundwater samples from the Mississippi River Valley Alluvial (alluvial) aquifer in Desha County, Arkansas (AR) have historically yielded elevated chloride concentrations (> 100mg/L). Overlapping spatial relationships between earthquake liquefaction sand-blows, soils derived from backswamp deposits, and chloride anomalies in the alluvial aquifer suggest the water quality conditions specific to southeast (SE) AR could be related to the tectonic and geomorphic features. Spatial analysis and statistical techniques are used to determine whether the chloride anomalies in the alluvial aquifer are more closely related to the spatial distribution of liquefaction sand-blows or surface soil types in Desha County.Pattern analysis suggests an underlying process is controlling the distribution of chloride concentrations in the alluvial aquifer. Cluster analyses show the chloride concentrations are more closely related to sand-blow densities than surface soil types, with high chloride concentrations associated with high sand-blow densities and low chloride concentrations associated with low sand-blow densities. Least squares regression analysis does not show a statistically significant spatial relationship between sand-blow densities, surface soil types, and chloride anomalies. However, the statistical relationship between sand-blow densities and chloride anomalies is stronger than surface soil types and chloride anomalies.The results from the spatial and statistical analyses are robust enough to conclude elevated chloride concentrations in the alluvial aquifer are more closely related to tectonic features than surface soil types in the study area. The chloride anomalies in the alluvial aquifer are interpreted to be from the intrusion of saline fluids from depth along faults during past earthquakes.

Effects of conservation wetlands on stream habitat, water quality and fish communities in agricultural watersheds of the lower Mississippi River Basin

Wetland conservation programs (e.g., Wetland Reserve Program and Conservation Reserve Program) have been implemented throughout the Mississippi River Basin to reduce environmental impacts from agricultural activities. However, there is limited information on the overall effectiveness of these programs on improving stream ecological conditions. To address this issue, replicate streams from southeastern Arkansas draining watersheds containing predominately croplands (n=4, termed “cropland”) and created wetlands (n=4, termed “wetland”) were monitored monthly from August 2012 through July 2013. Although repeated-measures analyses of variance (ANOVA) detected many significant time×stream type interactions, several habitat parameters and total habitat scores exhibited a general improvement in wetland streams. Some water quality conditions were better in wetland streams (e.g., lower turbidity, total suspended solids, and nutrient) compared to cropland streams. The time (season) effect was significant (p<0.05) for 13 of the 14 water quality parameters measured, meaning that water quality varied seasonally. Among the water quality parameters measured, three (water temperature, pH, and turbidity) exhibited significant (p<0.05) time×stream type interaction, meaning that the stream type effect was not consistent through time (seasons). Fish community sampling collected 6543 specimens from 12 species during the study period; 4410 and 2133 fish specimens were collected from cropland and wetland streams, respectively. Fish community metrics such as species diversity, species evenness, and species richness index were not significantly (p>0.05) greater in wetland streams. Overall, the conservation wetlands in the Lower Mississippi River Basin appear to have significantly improved stream habitat and moderately improved water quality, though no significant fish community effect was detected.

Common Denominators of Swainson's Warbler Breeding Habitat in Bottomland Hardwood Forest in the White River Watershed in Southeastern Arkansas

Abstract The most intensively studied breeding population of Limnothlypis swainsonii (Swainson's Warbler) is in the White River watershed of southeastern Arkansas. However, because vegetation sampling protocols employed at this site have been significantly different from those used elsewhere, it has been difficult for land managers to reconcile datasets across the species' range in order to construct consensus quantitative benchmarks for optimal breeding habitat in bottomland hardwoods. We used a standardized sampling protocol to compare the physiognomic and floristic characteristics of breeding territories at 2 sites in the White River watershed with comparable data from other populations in Arkansas, Mississippi, Louisiana, Florida, and Virginia. Breeding territories in the combined dataset for this rare migratory species varied substantially in successional stage, floristic diversity, hydrology, and management history. Visual screening provided by understory thickets of saplings, vine tangles, and shru...

Cool Water Off-flavor Algae and Water Quality in Four Arkansas Commercial Catfish Farms

Catfish pond culture during the cool weather period of late fall, winter and early spring have experienced problems related to algal populations. Geosmin tainting by off-flavor cyanobacteria is more abundant at this time. Toxic algae episodes also appear to be more common during cool weather periods, including the devastating new golden algae (Pyrmesium parvum) HAB, in adjacent Texas and believed to have occurred in Arkansas. Water and phytoplankton samples were collected weekly at 0800-1000 from November to April for three consecutive years from 12 ponds at 4 commercial catfish farms located in the southeastern Arkansas. Oscillatoria chalybea was found from November- January at low levels and Pseudanabaena limnetica occurred from January-April. Results from multiple regression show that the values of the expected number of Anabaena circinalis is significantly associated with dissolved oxygen, pH, total ammonia nitrogen, nitrite nitrogen, green algae, Chlorophyll a and Pheophytin a and the expected number of Oscillatoria chalybea is associated with total ammonia nitrogen, un-ionized ammonia, Pheophytin a cyanobacteria, and diatoms, whereas the expected number of Pseudanabaena limnetica is linked to temperature, total ammonia nitrogen and un-ionized ammonia, respectively.

Clarifying Details on a 1930s-Era Pine—Hardwood Stand in Arkansas

Abstract Data from recently discovered daily-work logs of US Forest Service (USFS) researcher Russell R. Reynolds enabled me to clarify a study I published a decade ago on a 1930s-vintage unmanaged, second-growth Pinus (pine)—hardwood stand in southeastern Arkansas. Though still too vague to reveal every detail, Reynolds' work logs confirmed a number of assumptions in the original paper and provided me with the background information to herein describe a more precise sampling framework for this 1930s-era study plot.

Shorebird Foraging Habitat in Southeast Arkansas

Approximately 500,000 shorebirds travel through the Mississippi Alluvial Valley (MAV) each spring and fall. During migration, the average 45g shorebird needs to eat approximately 8g of invertebrates per day. While shorebird stopover habitat guidelines for the MAV are based on an expert estimate of 2g of invertebrates/m2, this estimate has not been quantified in Arkansas. Invertebrate biomass available for shorebird foraging was examined on five properties in southeastern Arkansas during spring and fall migration (fall 2010, spring and fall 2011, and spring 2012). Macroinvertebrate biomass was less than the estimated 2 g/m2 in three of the four sampled seasons. Further validation of the expert invertebrate biomass estimate should be undertaken in the other regions of the MAV. These results suggest that current land management of shorebird stopover habitat in southeastern Arkansas is not providing adequate invertebrate forage to reach the current habitat management goals.

New Host and Location Record for the Bat Bug Cimex adjunctus Barber 1939, with a Summary of Previous Records

In June 2009, 14 Rafinesque’s big-eared bats(Corynorhinus rafinesquii) were collected from an abandoned house near Shepherd, San Jacinto County, Texas. Three individuals harbored bat bugs which were subsequently identified as Cimex adjunctus Barber 1939. This is the first record of this species from C. rafinesquii. In August 2013, 10 C. rafinesquii were collected from a maternity colony in Drew County in southeastern Arkansas. Four of the bats harbored bat bugs, which were identified as C. adjunctus. This is the first record of this bat bug from Arkansas. A summary of previous state and host records of the insect is provided, as is a summary of parasite records from C. rafinesquii.

Development of Near Infrared Spectral Models for Characterizing the Amy Soil Series

Physical and chemical properties of soils are routinely analyzed to assess site parameters and optimize ecological resources for precision farming, environmental monitoring, and soil survey and classification. Since existing standard laboratory methods are resource intensive, expensive, and time consuming, a convenient, rapid, economical, and ecologically viable technology is needed. The goal of this research was to evaluate the feasibility of using near infrared reflectance spectroscopy (NIRS) as an alternative analytical technique using 200 soil samples collected at depth increments of 0 to 15 and 15 to 30 cm in soils mapped as Amy silt loam in southeastern Arkansas. At the depth of 0 to 15 cm, NIRS successfully predicted several soil parameters, including sand (R2 = 0.85), silt (R2 = 0.80), clay (R2 = 0.91), N (R2 = 0.75), C (R2 = 0.77), C/N ratio (R2 = 0.78), P (R2 = 0.80), K (R2 = 0.83), Ca (R2 = 0.92), Mg (R2 = 0.92), Mn (R2 = 0.93), and B (R2 = 0.87). Similarly, at the depth of 15 to 30 cm, sand (R2 = 0.86), silt (R2 = 0.89), clay (R2 = 0.96), N (R2 = 0.79), C (R2 = 0.82), C/N ratio (R2 = 0.76), P (R2 = 0.88), K (R2 = 0.93), Ca (R2 = 0.89), Mg (R2 = 0.89), Na (R2 = 0.87), Mn (R2 = 0.96), Zn (R2 = 0.95), and B (R2 = 0.95) were well predicted. These results demonstrate that NIRS is a nondestructive, fast, accurate, reliable, cost effective, and ecologically viable analytical technique to augment standard laboratory methods for routine analyses of soil properties.

Tectonic history and setting of a seismogenic intraplate fault system that lacks microseismicity: The Saline River fault system, southern United States

Abstract Although the northwest-striking Saline River fault system of southeastern Arkansas is not defined by microseismicity, it is associated with sand blows and shows evidence of Pleistocene and Holocene surface ruptures, suggesting a significant seismogenic potential. This fault system is within the northern Gulf of Mexico interior coastal plain, a region only recently recognized as containing seismogenic faults. To better characterize this active fault system, we reconstructed its post-Paleozoic history using petroleum and coal industry wire-line well log and seismic reflection subsurface data. The Saline river fault system initiated as a series of northwest-striking grabens during Triassic/Jurassic uplift and incipient Gulf of Mexico rifting along the basement Alabama–Oklahoma transform margin of the North American Proterozoic craton. During post-rift subsidence, these grabens were buried by Gulf sediments until mid-Cretaceous uplift and igneous activity resulted in minor extensional reactivation of graben faults. Faulting style changed from extension to transpression during the Late Cretaceous due to compression of eastern North America as the North Atlantic rapidly widened and due to thermal weakening of the Alabama–Oklahoma transform lithospheric discontinuity as it obliquely crossed a mantle hot spot. In the Late Cretaceous, graben faults experienced contractional reactivation and steep, deeply-rooted transpressional faults developed within and parallel to the graben system. These transpressional faults locally displace Eocene, Pleistocene, and Holocene sediments. Fault activity continues on the Saline River fault system due to thin crust along the Alabama–Oklahoma transform and to high heat flow, which act together to weaken the crust and promote seismogenic tectonism. The fault system may lack appreciable microseismicity because the aftershock sequence of the last large earthquake has had time to dissipate.

Nikkei Baseball: Japanese American Players from Immigration and Internment to the Major Leagues by Samuel O. Regalado (review)

Reviewed by: Nikkei Baseball: Japanese American Players from Immigration and Internment to the Major Leagues by Samuel O. Regalado Robert A. Moss Samuel O. Regalado. Nikkei Baseball: Japanese American Players from Immigration and Internment to the Major Leagues. Urbana: University of Illinois Press, 2013. 208pp. Paper, $25. In Nikkei Baseball, Samuel Regalado, professor of history at California State University–Stanislaus, offers a cultural and social history of Japanese immigration and acclimatization in the United States, as refracted through the prism of Japanese American (or Nikkei) baseball. His chronology stretches from the Meiji restoration in Japan in 1870 to the imported Japanese major-league players and their Nikkei counterparts of the late twentieth century and early 2000s. In between, we get a bird’s-eye view of Nikkei baseball as it developed in the cities and towns of the western United States: Seattle, San Francisco, Los Angeles, Stockton, Sacramento, Portland, and Fresno. Nikkei Baseball is highly detailed; its relatively short text is buttressed by 44 pages of notes, sources, bibliography, and index. It ably charts the growth of Japanese American baseball from the first all-amateur Nikkei team in San Francisco in 1903, through the development of regional Nikkei tournaments, which recapitulated the growth of baseball in nineteenth-century America, to the formation of Nikkei leagues in the 1920s. Regalado posits that during the Meiji restoration in Japan, the feudal Samurai code of bushido melded with Western ideas of competitiveness and modernity, so as to reorder Japanese society while preserving Japanese traditions and identity. Baseball, introduced to Japan in 1872 by Horace Wilson, an educational reformer hired by the government, came to be viewed as an accompaniment of patriotism, industrial productivity, team play, and modernization. In 1878, Hiroshi Hiraoka, an engineer who had observed baseball in the United States, organized the first team in Japan, the Shimbashi Athletic Club. By 1890, Japanese universities were fielding nines, and in 1905 the Waseda University team toured the US, playing college teams in Washington, Oregon, and California. When the Issei (first generation) Japanese immigrants came to America, [End Page 151] they brought baseball with them, and the generational aspect of baseball connected them with their children, the Nisei. To the Issei, the game “nourished traditional virtues of loyalty, honor, and courage” (52). In turn, the Nisei developed leagues and tournaments. By 1926, the Southern California Japanese Baseball League had formed, centered around the large Nikkei community of Los Angeles. In the Fresno area, Kenichi Zenimura organized a league of ten teams. Games were also played with Mexican American, Negro league, and Pacific Coast League teams. Trumpeted by the Japanese American press, sports—especially baseball—were seen as a bridge to assimilation and an escape from discrimination. In the absence of permitted advance in other spheres, baseball provided an outlet. The LA Nippons barnstormed Japan in 1931, compiling a record of 20–5, and the Tokyo Giants visited Los Angeles to play the Nippons in 1935 and 1936. The Nikkei experience mirrored similar pathways followed by other immigrant groups, for example, Jews and Italians. Regalado also devotes considerable attention to the emergence of talented Japanese teams in Hawaii. By 1920, an all Japanese American baseball league was in operation there, and the first Nikkei major leaguers came from Hawaii. Nevertheless, Nikkei baseball remained a mostly segregated game through 1941, when Pearl Harbor ended an era. The “bridge” to assimilation had failed; the Nikkei were considered a nation apart. In February 1942, President Roosevelt signed the relocation order affecting all Japanese Americans on the west coast, moving them first into evacuation centers and then into relocation camps, “places where nobody had lived before and no one has lived since” (102). In these dire circumstances, all sports, especially “barbed-wire baseball,” provided a virtual escape. Despite a shortage of equipment, and rude diamonds scraped from unforgiving surroundings, evacuee teams were in action by mid-1943. “To the evacuees, sport was not an ‘innocuous aspect of life;’ it was an essential component to their mental and emotional survival in the camps” (105). At the Jerome camp in southeastern Arkansas, population 8,500, games drew 2,000-4,000 spectators. By 1944, the War Relocation Authority had authorized intercamp...

Composition, Biomass, and Overstory Spatial Patterns in a Mature Pine-Hardwood Stand in Southeastern Arkansas

A 1.21-ha plot was established in a mature pine–hardwood forest (Hyatt's Woods) along a low stream terrace in southeastern Arkansas. Compositionally, this stand had considerable arboreal richness, with 26 different tree species ≥9 cm in diameter. Loblolly pine (Pinus taeda) contributed 42% of the stand's 37.1 m2/ha of basal area; the remaining fraction included baldcypress (Taxodium distichum) and 24 hardwood species (no other single taxon exceeded 12%). Only a limited volume (15.2 m3/ha) of dead wood was encountered. The large size of the dominant conifers and abundance of high wood density hardwoods at Hyatt's Woods yielded a considerable quantity of biomass—at 317 Mg/ha, few stands in the region have more. With all species combined, tree stem location exhibited a random spatial pattern, but this changed when individual species were considered. For example, loblolly pine tended to be clustered on the higher portions of this relatively flat site, while white oak (Quercus alba) was well distributed across Hyatt's Woods, and baldcypress was associated with two abandoned stream channels. Unmanaged streamside forests in southeastern Arkansas usually contain high levels of arboreal diversity and biomass, and sometimes possess biological legacies that can date back centuries. These stands retain important structural and ecosystem service components in an otherwise increasingly fragmented and intensively managed landscape.

Comparing Aboveground Biomass Predictions for an Uneven-Aged Pine-Dominated Stand Using Local, Regional, and National Models

Sequestration by Arkansas forests removes carbon dioxide from the atmosphere, storing this carbon in biomass that fills a number of critical ecological and socioeconomic functions. We need a better understanding of the contribution of forests to the carbon cycle, including the accurate quantification of tree biomass. Models have long been developed to predict aboveground live tree biomass, but few of these have been derived from Arkansas forests. Since there is geographic variability in the growth and yield of pine as a function of genetics, site conditions, growth rate, stand stocking, and other factors, we decided to compare aboveground tree biomass estimates for a naturally regenerated, uneven-aged loblolly pine (Pinus taeda)-dominated stand on the Crossett Experimental Forest (CEF) in southeastern Arkansas. These predictions were made using a new locally derived biomass equation, five regional biomass equations, and the pine model from the National Biomass Estimators. With the local model as the baseline, considerable biomass variation appeared across a range of diameters—at the greatest diameter considered, the minimum value was only 69% of the maximum. Using a recent inventory from the CEF’s Good Farm Forty to compare each model, stand-level biomass estimates ranged from a low of 76.9 Mg/ha (a different Arkansas model) to as much as 96.1 Mg/ha (an Alabama model); the local CEF equation predicted 82.5 Mg/ha. A number of different factors contributed to this variability, including differences in model form and derivation procedures, geographic origins, and utilization standards. Regardless of the source of the departures, their magnitude suggests that care be used when making large-scale biomass estimates.

Deriving Biomass Models for Small-Diameter Loblolly Pine on the Crossett Experimental Forest

Foresters and landowners have a growing interest in carbon sequestration and cellulosic biofuels in southern pine forests, and hence need to be able to accurately predict them. To this end, we derived a set of aboveground biomass models using data from 62 small-diameter loblolly pines (Pinus taeda) sampled on the Crossett Experimental Forest in southeastern Arkansas. Of the 25 equations initially evaluated, we chose 17 that best fit our dataset and compared them using a suite of conventional test statistics, including pseudo-R2 , root mean squared error (RMSE), and bias. Because most of the 17 models varied little in pseudoR 2 (ranging between 0.96 and 0.99), bias (all were within ± 0.01), and RMSE, an additional comparison was done using Akaike’s Information Criterion corrected for small sample size (AICc). This test statistic produced considerably more discrimination between the biomass models. Of the 17 models evaluated, six produced ΔAICc scores that met or exceeded the threshold for substantial support. To recommend a single preferred model, we then extrapolated beyond our actual data and qualitatively compared model predictions with those from the National Biomass Estimator. Our “best” model did not have the minimum AICc score, but rather predicted logically consistent aboveground biomass values at both the upper and lower ends of our extrapolation.